While noise, one of the most prevalent occupational hazards, is well recognized as a cause of high frequency hearing loss, a growing body of evidence suggests that organic solvents, also widespread in industry, may also increase the risk of hearing loss. There is a need for longitudinal studies of exposed workers to further investigate this possibility. Determining a dose-response relationship for solvents and hearing loss could affect further efforts to control exposures and prevent hearing loss. This study will make use of the Alcoa database, a unique longitudinal set of a large working population which includes a significant number of women and African Americans. This data set contains both detailed exposure information regarding noise and solvents as well as hearing tests on employees in U.S. Alcoa facilities. Preliminary study of this database reveals that noise hearing loss is a significant problem, and that a significant number of workers are exposed to solvents. The long term goal of the study is to examine effects of chronic solvent exposure on hearing, as well as the impact of noise-solvent interactions on the auditory system. The study will investigate these effects through a longitudinal cohort study of 8800 worjers hired at Alcoa between 1983 and 1997. This would be the largest study to date of noise, solvents, and hearing, and will allow for calculation of relative risks of developing hearing lost for solvent and noise exposed workers. Modeling of industrial hygiene sampling data will allow for cumulative estimates of noise and solvent exposures. A nested case control study will match cases of hearing loss identified in the cohort with controls by age at hire, year of hire, sex, and gender, to further explore these relationships.